MITOGENIC ACTIONS OF ENDOTHELIN‐1 AND EPIDERMAL GROWTH FACTOR IN CULTURED AIRWAY SMOOTH MUSCLE

Abstract

1. Hyperplasia of airway smooth muscle contributes to the increase in bronchomotor responsiveness that characterizes asthma. We have investigated the mitogenic potential of endothelin‐1 (ET‐1) and epidermal growth factor (EGF) in guinea‐pig cultured airway smooth muscle and the relationship of these actions to tyrosine phosphorylation and increases in intracellular calcium (Ca2+i). 2. ET‐1 stimulated DNA and protein synthesis and also increased cell number, but these mitogenic actions were small compared with those of EGF. 3. ET‐1 and EGF increased the level of tyrosine phophorylation of a range of proteins with apparent molecular weights between 80 and 100 kDa and also increased phosphoryla..